Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06126 (CD1a)
 2,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of a battery of CD1 mAb on intracellular free Ca2+ concentration and IL-2 production has been examined on different T cell lines in this study. Both 0249F and NU-T2 two CD1b specific mAb tested, induced a rapid increase in the intracellular Ca2+ concentration on HPBALL T cells whereas only one (L161) among three different CD1c mAb (L161, 10C3, and M241) produced a similar effect. In contrast the addition of four different CD1a mAb directed against two different epitopic groups of this molecule were uneffective in modifying the intracellular Ca2+. Both L161 and 0249F also induced a comparable increase in the intracellular Ca2+ concentration on MOLT 4 and JURKAT, two other T cell lines of similar phenotype. The effect of L161 mAb on the IL-2 production of the IL-2 producing T cell line JURKAT was also examined. The association of the latter with PMA strongly induced the production of IL-2 on this cell model while either L161 or PMA alone had no effect. Although the natural ligand and the function of CD1 molecules are still unknown, the accumulation of these data strongly suggest that CD1b and CD1c might represent two activatory pathways for immature T cells operating before the classical CD2 and CD3 activation pathways.
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PMID:CD1 stimulation of human T cell lines induces a rapid increase in the intracellular free Ca2+ concentration and the production of IL-2. 169 Jul 69

In recent years, several studies have confirmed the clonal elimination of thymocytes with receptors that recognize Ag and MHC molecules present on the membrane of thymic stromal cells, a process that may be relevant to the establishment of self-tolerance. In our work, we show that anti-CD3 treatment of single positive CD4+ or CD8+ human medullary thymocytes (obtained by anti-CD1a plus C) induces their apoptotic death. Some events commonly associated with the early steps of normal activation (IL-2R expression, increase in cytoplasmic Ca2+) are also induced after anti-CD3 treatment. Nevertheless, IL-2 is not secreted by these activated cells. The addition of exogenous IL-2 inhibits the apoptosis induced by anti-CD3. We suggest that the lack of secretion of IL-2 by medullary thymocytes may be a physiologic mechanism implicated in the process of negative selection that leads to tolerance.
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PMID:IL-2 protects against anti-CD3-induced cell death in human medullary thymocytes. 197 64

The thermotropic behavior (studied by high-sensitivity differential scanning calorimetry) and susceptibility to Vibrio cholerae sialidase hydrolysis of large unilamellar vesicles of dipalmitoyl-phosphatidylcholine, containing native GD1a ganglioside or the molecular species of GD1a containing C18:1 or C20:1 long-chain base (C18:1 GD1a; C20:1 GD1a), were studied. Vesicles containing ganglioside (10% in molar terms) showed the presence in the heat capacity function of a second minor peak besides the phospholipid main transition peak. The presence of a second peak is much more evident with C20:1 GD1a than with C18:1 GD1a, the difference being potentiated by Ca2+ and indicating a different tendency of the CD1a molecular species to undergo lateral phase separation. The scans of vesicles containing native GD1a showed the features of those obtained with C18:1 GD1a and C20:1 GD1a, indicating that the main components of native GD1a, C18:1 GD1a and C20:1 GD1a, maintain their individual aggregative properties. V. cholerae sialidase affects vesicle-bound GD1a at a much higher rate (17-25-fold) than it does micellar GD1a, the activation by Ca2+ being 3- and 2-fold, respectively. The Vmax values were identical on C18:1 GD1a and C20:1 GD1a in micellar dispersions, whereas they were markedly higher (from 20 to 50%) on C18:1 GD1a than on C20:1 GD1a in vesicular dispersions. Exhaustive sialidase hydrolysis of vesicles carrying native GD1a produced C18:1 GM1 and C20:1 GM1 in the same proportion as the C18:1 and C20:1 species present in native GD1a (53.9% and 46.1%).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interactions of proteins with ganglioside-enriched microdomains on the membrane: the lateral phase separation of molecular species of GD1a ganglioside, having homogeneous long-chain base composition, is recognized by Vibrio cholerae sialidase. 320 23

Epidermal Langerhans cell heterogeneity is poorly understood with regard to phenotypic characteristics, such as the expression of human leukocyte antigen (HLA)-DR, integrin, and Fc receptor molecules, as well as functional characteristics, such as the ability to process and present antigens or produce cytokines during various phases of immigration and maturation. Technical limitations of Langerhans cell number have limited functional assays on putative Langerhans cell subsets in in vivo epidermis. Therefore, we used flow cytometry for simultaneous phenotypic and functional assessment at the single-cell level within the Langerhans cell population. Freshly isolated human epidermal cell suspensions were stained with a battery of monoclonal antibodies, including anti-HLA-DR, -CD1a, -CD1c, -CD11c, -Fc gamma RII, and -Fc epsilon RI. Two distinct Langerhans cell subsets were identified by their different levels of HLA-DR expression. The DRHi subset expressed higher amounts of CD11c and exhibited greater cytoplasmic complexity and higher baseline calcium than the DRLo subset (p < or = 0.03 for each). Some subjects also expressed high levels of Fc epsilon RI in the DRHi, CD11cHi subset. To determine whether these phenotypic subsets may exhibit differential signal-transduction functional properties, Langerhans cells were partially enriched over Ficoll-Hypaque and their cytosolic mobilization after the addition of ionomycin was analyzed using the calcium indicator, indo-1, in conjunction with quantitative analysis of HLA-DR expression. By this real-time flow cytometric analysis, a new subpopulation was revealed within the DRLo Langerhans cell subset. This subset increased its cytosolic calcium concentration much more than the other two subsets (change in indo-1 blue:violet emission ratio of 37.33 +/- 2.34 in the Hi Flux DRLo subset versus 13.23 +/- 0.29 in the Lo Flux DRLo subset, and versus 7.6 +/- 2.99 in the Lo Flux DRHi subset). These data indicate that functional, as well as phenotypic, subsets of Langerhans cells exist within normal human epidermis. Their responses to physiologic stimuli may relate to maturational stage or the level of in vivo activation.
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PMID:Differential responsiveness of Langerhans cell subsets of varying phenotypic states in normal human epidermis. 752 45

In this study, we analyzed the expression and function of the lymphocyte surface lectin NKRP1A on peripheral blood monocytes (Mo) or Mo and dendritic cells (DC) derived from thymic and bone marrow precursors. De novo expression of NKRP1A and CD14 molecules was detected upon culture of CD2- CD3- CD14- CD16- CD1a- NKRP1A- immature thymic precursors for 7 days in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF). Under these culture conditions, by day 21, a fraction of cells had lost CD14 and acquired both CD80 (B7.1) and CD86 (B7.2) molecules. These cells displayed a DC-like morphology and were surface NKRP1A positive. CD34+ NKRP1A- CD14- precursors, isolated from bone marrow and cultured in the presence of GM-CSF, also expressed both NKRP1A and CD14: these antigens were newly expressed on about one third of cells which had lost the CD34 precursor marker. In addition, NKRP1A was constitutively present on resting CD14+ peripheral blood Mo. When these cells were cultured in the presence of GM-CSF, the resulting DC population retained the expression of NKRP1A and acquired CD80, while they lost the CD14 antigen. Functional analysis revealed that the engagement of NKRP1A molecule leads to a strong intracellular calcium ([Ca2+]i) increase both in resting peripheral blood Mo and in vitro-derived DC. [Ca2+]i increase was mainly due to extracellular calcium influx, as it was completely abrogated by the addition of EGTA. More importantly, the engagement of the NKRP1A molecule induced interleukin (IL)-1 beta and IL-12 production by resting Mo and DC, respectively. Altogether these data indicate that NKRP1A lectin is present at the surface of Mo and DC and may play a relevant role in the activation and function of both cell types.
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PMID:Expression and function of NKRP1A molecule on human monocytes and dendritic cells. 939 25

To determine whether human CD4+ T cells undergo post-thymic maturation, we compared the susceptibility to anergy induction in human thymic CD1a- CD4+ single-positive (CD4+), cord blood (CB) CD4+, and adult peripheral blood (APB) CD4+ T cells by stimulation with toxic shock syndrome toxin-1 (TSST-1). Most TSST-1-induced T cell blasts derived from either T cell preparation expressed TCR Vbeta2, which determines the potential reactivity to TSST-1. Most thymic CD4+ T cell blast preparations exhibited little or no production of IL-2 and IL-4 after restimulation with TSST-1 and only marginal responses after stimulation with rIL-2 or a combination of PMA and calcium ionophore, while the APB CD4+ T cell blasts showed high responses to these stimuli. The responses of CB CD4+ T cell blasts to these stimuli varied, ranging from minimal to relatively high. Studies of DNA fragmentation showed that there was no significant cell death of thymic CD4+ T cell blasts. Most thymic CD1a- CD4+ and CB CD4+ T cells were CD38 positive. APB CD4+ T cell blasts derived from the CD38+ fraction and from the CD38- fraction exhibited equally high responses to restimulation with TSST-1. These results indicate that thymic CD1a- CD4+ and CB CD4+ T cells are inherently highly susceptible to anergy induction by bacterial superantigens and that thymic CD1a- CD4+ T cells are less mature than CB CD4+ T cells, suggesting that post-thymic maturation in thymic T cells migrating to the periphery is required for acquisition of full reactivity to antigenic stimulation.
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PMID:Post-thymic maturation of migrating human thymic single-positive T cells: thymic CD1a- CD4+ T cells are more susceptible to anergy induction by toxic shock syndrome toxin-1 than cord blood CD4+ T cells. 955 63

Dendritic cells (DC) that are stimulated with inflammatory mediators can maturate and migrate from nonlymphoid tissues to lymphoid organs to initiate T cell-mediated immune responses. This migratory step is closely related to the maturation of the DC. In an attempt to identify chemokine receptors that might influence migration and are selectively expressed in mature DC, we have discovered that the chemokine receptor, EBI1/CCR7, is strikingly up-regulated upon maturation in three distinct culture systems: 1) mouse bone marrow-derived DC, 2) mouse epidermal Langerhans cells, and 3) human monocyte-derived DC. The EBI1/CCR7 expressed in mature DC is functional because ELC/MIP-3beta, recently identified as a ligand of EBI1/CCR7, induces a rise in intracellular free calcium concentrations and directional migration of human monocyte-derived mature DC (HLA-DRhigh, CD1a(low), CD14-, CD25+, CD83+, and CD86high) in a dose-dependent manner, but not of immature DC (HLA-DRlow, CD1a(high), CD14-, CD25-, CD83-, and CD86-). In contrast, macrophage inflammatory protein-1alpha (MIP-1alpha), monocyte chemotactic protein-3 (MCP-3), and RANTES are active on immature DC but not on mature DC. Thus, it seems likely that MIP-1alpha, MCP-3, and RANTES can mediate the migration of immature DC located in peripheral sites, whereas ELC/MIP-3beta can direct the migration of Ag-carrying DC from peripheral inflammatory sites, where DC are stimulated to up-regulate the expression of EBI1/CCR7, to lymphoid organs. It is postulated that different chemokines and chemokine receptors are involved in DC migration in vivo, depending on the maturation state of DC.
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PMID:EBI1/CCR7 is a new member of dendritic cell chemokine receptor that is up-regulated upon maturation. 974 76

In the defense against Mycobacterium leprae, macrophages play an essential part in the mechanism of bacterial lysis but require the presence of cytokines such as interleukin 2 and gamma interferon from lymphocytes in order to effectively kill the organisms in any number. While there have been many studies of the lymphocytes in lesions of leprosy, less attention has been given to the immunohistochemical characterization of the macrophage populations. In this study, the cutaneous lesions of 69 patients with leprosy (42 lepromatous, 5 mid-borderline, and 22 tuberculoid) were evaluated by immunohistochemistry for the expression of S100 protein, CD1a, CD68, muramidase, HLA-DR, and Factor 13a. The macrophages from lesions of polar, subpolar, and borderline lepromatous leprosy patients expressed S100 protein intensely and constantly. In contrast, the lesions of polar and subpolar tuberculoid leprosy had very few cells that were immunoreactive for S100 protein ('S100+') in the granulomas in the dermis. The macrophages in all lesions were reactive for CD68 and muramidase. In paraffin sections, macrophages of lepromatous lesions failed to stain for HLA-DR, whereas in tuberculoid lesions, they were strongly positive for HLA-DR. Three patients with histoid leprosy (relapse lesions) had lesions that were strongly positive for Factor 13a and were negative for S100 protein ('S100-'). Given the possible chemotactic and migration inhibition effects of the calcium-binding proteins of the S100 family, these data suggest a possibly important role for S100 protein in the accumulation of macrophages in lepromatous leprosy, and also reveal infection of Factor 13a + dermal dendritic cells in histoid leprosy.
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PMID:Multibacillary leprosy: lesions with macrophages positive for S100 protein and dendritic cells positive for Factor 13a. 987 Jun 71

Chemokines are involved in the control of dendritic cell (DC) trafficking, which is critical for the immune response. We have generated DC from human umbilical cord blood CD34+ progenitors cultured with granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha (TNF-alpha), and stem cell factor. Using an anti-CCR6 monoclonal antibody, we observed that these cells showed maximum expression of this beta-chemokine receptor when they were immature, as determined by their relatively low expression of several DC maturation markers such as CD1a, CD11c, CD14, CD40, CD80, and CD83. Immature DC responded strongly to macrophage inflammatory protein-3alpha (MIP-3alpha), the CCR6 ligand, in migration and calcium mobilization assays. CCR6 expression decreased in parallel with the DC maturation induced by prolonged TNF-alphaq treatments. Interleukin-4 was also able to decrease CCR6 protein levels. Our findings suggest that the MIP-3alpha/CCR6 interaction plays an important role in the trafficking of immature DC to chemokine production sites such as injured or inflamed peripheral tissues, where DC undergo maturation on contact with antigens.
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PMID:Down-regulation of the beta-chemokine receptor CCR6 in dendritic cells mediated by TNF-alpha and IL-4. 1057 17

The CD1 molecules exhibit characteristics of the MHC class I and class II molecules. They are expressed on cortical thymocytes and, similarly to MHC class II molecules, on antigen-presenting cells. In the present study, we investigated the role of the CD1 molecules in the T-cell response to bacterial superantigens. Indeed, we have observed that CD1 molecules could be detected on the CD14-positive population of some healthy donors (14% of donors tested). The CD1 expression on monocytes is correlated with an activation state of the donors as demonstrated by the increased expression of the CD25, CD38, CD45R0, and MHC class II molecules on their lymphocytes. On these donors, CD1a mAbs induced a clear inhibition (65%) of lymphocyte proliferation induced by either staphylococcal enterotoxin A or toxic shock syndrome toxin-1, whereas this proliferation was constantly unaffected by the addition of mAbs directed against CD1b or CD1c. Moreover, an intracellular calcium flux was induced in monocytes following CD1a engagement, and this calcium flux was partially inhibited by preincubation of these cells with the superantigen. These results attribute to the CD1a molecule expressed by monocytes a role in the transduction of signal(s) involved in superantigen-induced activation.
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PMID:Human CD1a molecule expressed on monocytes plays an accessory role in the superantigen-induced activation of T lymphocytes. 1068 9


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